Before seriously considering the argument about convergence and humanoids, it is worth remembering that we are reacting to a book review. And the one thing we know from the review is that it was written by a New Atheist. Thus, the default position is that it is a biased review, so we might reasonably expect Coyne to be arguing against a straw man. That Coyne has to cut-and-paste from Miller's first book to make a sneering point about his second book tells us Coyne has his own agenda.

If you want to seriously ponder the convergence argument, you would have to look more beyond Coyne's biased review and presentation of arguments he feels forced to debunk. In fact, you would have to go beyond the books from Miller and Giberson. For it was Simon Conway Morris who put this argument on the table, back in 2003, in his book, Life's Solution: Inevitable Humans in a Lonely Universe.

Suffice it to say that Morris is enough of an expert on evolution to be well aware of the type of criticisms Coyne makes. Thus, one might also assume that his argument is more sophisticated and nuanced than the characterization Coyne supplies.

So I went looking for my copy. I started reading this book years ago, but only made it halfway through. I finds it and it turns out that Morris has a chapter (9) entitled, "The non-prevalence of humanoids?" I just started reading this chapter (Morris's views are extremely similar to my views on front-loading) and I can tease you with this part early in the chapter:

"There is no simple answer to the question about the stage at which something like ourselves becomes overwhelmingly probable. To provide a focus, however, much of this chapter will concentrate on those elements that we might regard as the hallmarks of the humanoid - large brain, intelligence, tools, and culture - all of which, needless to say, show examples of convergence." (p. 234)

PS: Go back and consider Coyne's objection:

"We recognize convergences because unrelated species evolve similar traits. In other words, the traits appear in more than one species. But sophisticated, self-aware intelligence is a singleton: it evolved just once, in a human ancestor."

Coyne is basically saying that in order to show that humans are special, they shouldn't be special. If the planet was populated with two or three other species of sophisticated, self-aware intelligent species, would this really make it clear that humans were intended? Heads I win; tails you lose.

2. Agreed. Though I suspect Coyne would say that the scientific evidence is not consistent with an intent for convergence to humanoid creatures. That's a little softer than disproving it but close.

How would or could anyone get proof of 'intent' in a scientific way here? Though I don't necessarily agree with Miller & company's specific claims on this, that humans were an outcome of evolution is in this discussion without dispute - if it's agreed that evolution produced humans, it goes without saying that a mind could use evolution to produce humans. Convergence certainly plays a role in evolution, and could play a role in producing such an end product.

It also seems to me that, at one point in history, a convergent outcome in evolution would/could have been singular - such that at that point, one would look around and say, 'Well, that was an entirely unique development.' Go further along the timeline, and oh - actually this development is repeating. If evolution does tend towards repeating solutions and developments along distinct lineages, it lends force to the argument Miller & company seem to be making - especially if part of the assumption is that once a species reaches a human-like stage, their influence spreads rapidly and powerfully enough that a second 'natural' development of such intelligence in the same environment is vastly reduced.

The point where science ends and speculation begins really seems to be shorter than many realize, no matter what side they take in such debates. Coyne himself seems to hardly care about such lines, save for insisting that he can always imagine chance as being fundamental no matter what the issue.